Hydrocracking of cycle oils with preliminary solvent extraction to remove coke forming constituents



.J. W. MYERS ET L HYDROCRACKING OF CYCLE OILS WITH PRELIMINARY SOLVENT EXTRACTION TO REMOVE COKE FORMING CONSTITUENTS Filed Dec.

INVENTORS J. w MYERS BY E. DREHMAN ATTORNEYS Feb. 28, I967 United States Patent 3,306,840 HYDROCRACKING 0F CYCLE OILS WITH PRE- LIMINARY SOLVENT EXTRACTION T0 RE- MOVE COKE FORMING CONSTITUENTS John W. Myers and Lewis E. Drehman, Bartlesville, 0k]a.,

assignors to Phillips Petroleum Company, a corporation of Delaware Filed Dec. 18, 1964, Ser. No. 419,338 6 Claims. (Cl. 20887) This invention relates to hydrocracking. In one of its aspects it relates to the hydrocracking of a heavy cycle oil, for example, a heavy cycle oil produced in catalytic cracking, by dividing said oil into two portions, a low boiling portion and a high boiling portion, and extracting the high boiling portion with propane and then recombining the propane soluble fraction (extract) and the low boiling portion and then hydrocracking the combined portions. In another of its aspects, a heavy cycle oil to be hydrocracked is separated into at least two portions, a heavy portion, i.e., high boiling material constituting about to 20 percent of the heavy cycle oil, this portion is extracted with propane to obtain an extract and a raffinate and the extract is combined with the remainder of the heavy cycle oil and then hydrocracked, resulting in a considerably reduced coke formation over that necessarily obtained without practicing the present invention.

The hydrocracking of heavy cycle oil and other oils is well known. In the catalytic cracking or conversion of petroleum hydrocarbon stocks or oils, there is produced a synthetic crude oil or catalytic cracking effluent. This efiluent can be distilled as is known, to produce various fractions among which is produced, currently, a fraction known as heavy cycle oil. Heavy cycle oils, as is well known, are obtained in fractionating an efiluent as described and have an initial boiling point of about 500 F. to 675 F. and includes fractions which can boil as high as 900 F. The following is an example of a heavy cycle oil to which this invention can be particularly advantageously applied:

'API gravity 24.2

Distillation, F.:

IBP -500 5% 550 665 30 695 50 710 70 725 90 740 95 770 EP 820 Sulfur, wt. percent 0.42

Nitrogen, p.p.m 490 Hydrocracking of high molecular weight petroleum stocks has a number of advantages over simple catalytic cracking of the same stocks: (1) it permits operation at considerably lower temperatures, e.g., 550850 F. instead of 900-1100 F.; (2) it minimizes coke formation, thus permitting very long on-stream periods, which results in considerably higher productivity from a given cracking unit; and (3) it minimizes light gas formation, which means that the light gas separation facilities can be considerably smaller and that excess C and C hydrocarbons are not produced to compete with the large amounts of those hydrocarbons available from natural gasoline. With virgin gas oils coke formation is low enough that continuous operation is usually possible. However, when the hydrocracking charge stock is a heavy cycle oil produced in catalytic cracking, considerably higher coke formation occurs and cyclic operation with catalyst regeneration is often required.

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We have found that coke formation in the hydrocracking of heavy cycle oil produced in catalytic cracking is markedly reduced by removing the high-boiling material from the cycle oil, extracting this high-boiling material with propane, combining the extract from this extraction with the low-boiling material resulting from the fractionation to remove the high-boiling material from the cycle oil, and charging the combined material to the hydrocracking unit. As a result of this lowered coke formation, the on-stream period can be greatly lengthened at a given severity of operation, or a greater depth of conversion can be obtained during the same on-stream period.

It is an object of this invention to provide a hydrocracking operation. It is another object of this invention to provide a process for the hydrocracking of a heavy cycle oil or other oils, particularly an oil resulting from catalytic cracking, in which process coke formation is considerably reduced. It is a further object of this invention to provide a combination of steps in an operation including hydrocracking of a feedstock resulting in coke formation wherein the feedstock is treated to remove therefrom those constituents which, it has been found, contribute to form a substantial portion of the coke which results in a hydrocracking operation of the character with which this invention deals.

Other aspects, objects and the several advantages of this invention are apparent from this disclosure, the drawing and the appended claims.

According to the present invention, coke formation in a hydrocracking operation i considerably reduced by pretreating the feed to remove therefrom coke forming materials which are found in the higher boiling portion thereof, and which can be removed with a solvent which possesses the solvent characteristics of propane under pro pane extraction conditions.

In its now preferred form, the invention is applied to a heavy cycle oil produced in catalytic cracking by known methods. The heavy cycle oil is divided into two portions, namely a low boiling portion and a high boiling material. The high boiling portion constitutes approximately 5 to about 20 percent of the feed. This 5-20 percent is extracted with a solvent such as propane to obtain an extract and a raffinate. The extract is combined with the low boiling portion and this constitutes, essentially, the feed to the hydrocracking operation. As will be understood by one skilled in the art having studied this disclosure, other oils can be combined with this feed for purposes of the hydrocracking operation.

The process of our invention is carried out continuously in well-known types of equipment, within the following ranges of operation conditions:

The active hydrocracking ingredient or catalyst is selected from those known to the industry, i.e., the Group VI-B (Langes Handbook of Chemistry, Eighth Edition, pp. 56-57), oxides and sulfides and the Group VIII metals, oxides, and sulfides or mixtures thereof. Usually a Group VI-B oxide or sulfide is used together with a Group VIII metal, oxide, or sulfide whereas a Group VIII metal, oxide, or sulfide is frequently used alone. Exemplary of active hydrocracking ingredients that can be used are platinum, palladium, nickel, cobalt, nickel oxidemolybdenum oxide (frequently referred to as nickel molybdate), iron sulfide, nickel sulfide, cobalt sulfide,

cobalt oxide-molybdenum oxide (frequently referred'to as cobalt molybdate), cobalt sulfide-molybdenum sulfide, nickel oxide-tungsten oxide (frequently referred to as nickel tungstate), nickel sulfide-tungsten sulfide, tungsten sulfide, and the like. The active ingredient, or each of the active ingredients if there is more than one, can be present (as metal) to the extent of 0.1 to 25 weight percent, preferably 1 to 15 weight percent of the support. We prefer to use a nickel tungstate or a nickel molybdate catalyst, which we have found to be equivalent. Quite frequently the catalyst is sulfided by treating with a material such as carbon disulfide before use. It is also possible to obtain the same effect by operating with a sulfiding material in the feed, or by both pre-sulfiding and operating With a sulfiding material in the feed.

The invention is described herein particularly with reference to a silica-alumina support, but any of the known acidic supports can be used to prepare catalysts for the process of our invention. Exemplary of other acidic supports are silica-Zirconia, silica-alumina-zirconia, silicamagnesia, silica-alumina-magnesia, silica-thoria, silicaalumina-thoria, alumina-boria, and the like. The support used can optionally be treated with steam to decrease the acidity or with a halogen or halogen acid to increase the acidity.

Referring now to the drawing, a heavy cycle oil as described herein is passed by 1 into fractionator 2 wherein it is divided into two portions, an overhead 3 and a bottoms 4, the latter constituting 5 to 20 percent of the total feed entering at 1. The bottoms are passed to solvent extraction zone 5 into which propane is fed at 6. A propane insoluble fraction is removed at 7 while a propane soluble fraction is passed by 8, after removing solvent, by means not shown, into admixture with overhead 3 constituting the feed 9 to hydrocracking zone 10 from which hydrocracked products are removed at 11. When solvents other than propane, butane or the like are used, they are introduced at 6'.

It will be understood by one skilled in the art in possession of this disclosure, having studied the same, that varying feeds presenting a coking problem can be employed and that the precise percentage of the overall feed which is subjected to solvent extraction can be determined readily by mere routine tests.

Although the process of the invention is illustrated with a feed prepared by propane extraction, it is Within the scope of the invention to use other solvents, such as liquid sulfur dioxide, dimethyl sulfoxide, phenol, nitrobenzene, chlorophenol, trichloroethylene, cresylic acid, pyridine, furfural, 2,2-dichloroethyl ether, liquid butane or isobutane, cresol, and mixtures thereof. It should be understood that when solvents other than propane or butanes are used, it is the raffinate which is recombined with the low boiling fraction. Typical, but not limiting, conditions for the propane extraction step are:

Solvent to oil ratio 3/1 to /1 Temperature, F 140 to 220 Pressure, p.s.i.a 300 to 700 Contacting stages 2 to 4 Various refinements of solvent extraction or refining which are known in the art are applicable in the carrying out of the present invention. If desired, the heavy cycle oil fraction or portion which is subjected to the solvent extraction can be diluted or admixed with another oil prior to the extraction step. Some or all of this oil can constitute a part of the ultimate feed to Zone 10. When such an oil is added, it is preferably added by 12.

Example I A nickel tungstate catalyst was prepared by impregnating a portion of 10-28 mesh cogelled 33 silica-67 alumina with sufficient aqueous solution of ammonium metatungstate and nickel nitrate to give a catalyst containing 1.4 weight percent nickel and 9.6 weight percent tungsten.

The composite was dried overnight at about 215 F., and calcined for one hour at 1100" F. The catalyst was reduced and sulfided before use by heating it in hydrogen 2 hours at 570 F. and atmospheric pressure, increasing the pressure to 2000 p.s.i.g. and continuing hydrogen flow for about 1.1 hours, and then passing over the catalyst normal hexane containing about 5 Weight percent carbon disulfide at 2000 p.s.i.g and 2 LHSV for 4.9 hours.

The feed used was a Gulf Coast 600 F plus, heavy cycle oil, which constituted the higher-boiling 60 percent of the total heavy cycle oil from a catalytic cracking operation.

Operating conditions used are 740 F., 2000 p.s.i.g., 8000-9000 cu. ft. of hydrogen per barrel, and 0.5 LHSV.

A 46 day run is made in which the two following feeds are charged alternately; Feed II is charged during the first 19 and last 11 days, and Feed I is charged during the middle 16 days:

Feed I:

Heavy cycle oil. Feed II:

Lower-boiling 84 percent of the heavy cycle oil plus the extract from propane extraction of the higher boiling 16 percent of the heavy cycle oil.

Coke formation is determined (after initial lining out) during the operating periods with the different feeds:

Coke, lb./ lb. catalyst/hr.:

Feed I s 0.0015 Feed 11 0.0005

It will be noted-that the coke formation can be reduced by a factor of about 3 when about 5 to about 20 percent of the high boiling material is removed from the feed for heavy cycle oil and treated according to the present invention.

Reasonable variation and modification are possible Within the scope of the foregoing disclosure, the drawing and the appended claims to the invention, the essence of which is that prior to hydrocracking a heavy cycle oil, especially an oil obtained by catalytic cracking, the oil is divided into at least two portions, a light portion and a heavy or high boiling portion, the high boiling portion is solventextracted with a solvent which will remove therefrom those high-boiling, coke-forming constituents which propane will reject therefrom under solvent extracting conditions, the balance of the high boiling portion is then combined with the light portion and the combined portions are hydrocracked.

We claim:

1. A process for the hydrocracking of a heavy cycle oil. produced by cracking which comprises dividing said cycle oil into two portions, a low boiling portion and a high boiling portion, solvent extracting the high boiling portion to remove coke forming constituents therefrom, combining the thus treated high boiling portion and the low boiling portion and subjecting the combined material thus obtained to hydrocracking.

2. A process according to claim 1 wherein the high boiling portion constitutes approximately 5-2O percent of the heavy cycle oil.

3. An improved process for hydrocracking heavy cycle oil produced in catalytic cracking which comprises dividing said oil into two portions, a major low boiling portion and a minor high boiling portion, solvent extracting said high boiling portion to remove coke forming constituents therefrom, combining the thus treated high boiling portion with the low boiling portion and subjecting the combined portions to hydrocracking.

4. An improved process for hydrocracking heavy cycle oil produced in catalytic cracking which comprises removing from said heavy cycle oil approximately 5-20 percent of the higher boiling materials therein, propane solvent extracting said removed portion to obtain an extract and a raflinate, combining the extract thus obtained with the remainder of said heavy cycle oil and subjecting the combined material to hydrocracking.

5. A process for the hydrocracking of a catalytically derived heavy cycle hydrocarbon oil which comprises removing approximately 5 to 20 percent of the higher boiling constituents thereof, solvent extracting said constituents with a solvent selected from propane, butane and isobutane to obtain an extract and a rafllnate, combining the extract thus obtained with the remainder of the original oil and subjecting the combined material thus obtained to hydrocracking under hydrocracking conditions including a temperature in the approximate range 500- 900 F. with a pressure in the approximate range of 500-5000 p.s.i.g., hydrogen in standard cubic feet per barrel of approximately 500l2,000, and a liquid hourly 15 6 space velocity of the gas-oil of approximately 0.1-10.

6. A process according to claim 5 wherein the conditions are a temperature of 550-850 F. with a pressure in the range of 1000-3000 p.s.i.g., hydrogen in standard cubic feet per barrel of 4500-10,000, and a liquid hourly space velocity of the gas-oil of 0.4-3.

References Cited by the Examiner UNITED STATES PATENTS 3,227,645 1/1966 Frumkin et a1 20886 DELBERT E. GANTZ, Primary Examiner.

ABRAHAM RIMENS, Examiner. 

1. A PROCESS FOR THE HYDROCRACKING OF A HEAVY A CYCLE OIL PRODUCED BY CRACKING WHICH COMPRISES DIVIDING SAID CYCLE OIL INTO TWO PORTIONS, A LOW BOILING PORTION AND A HIGH BOILING PORTION, SOLVENT EXTRACTING THE HIGH BOILING PORTION TO REMOVE COKE FORMING CONSTITUENTS THEREFROM, COMBINING THE THUS TREATED HIGH BOILING PORTION AND THE LOW BOILING PORTION AND SUBJECTING THE COMBINED MATERIAL THUS OBTAINED TO HYDROCRACKING. 